Techniques and equipment are now available for direct culturing of the sinuses and of the lower respiratory tract, for preparation of microbial antigens and for delineation of the mechanisms of allergic reactivity. Appropriate patients are available to our group for such an intensive study. The purpose of the proposed study is to identify and compare the microorganisms present in the sinuses and in the lower respiratory tract of patients with chronic bronchitis associated with bronchospasm and to characterize the dermal reactivity (i.e., reagin, Arthus or tuberculin-type delayed responses) to antigenic fractions of these microorganisms in such patients. A special effort will be made to learn: 1) if tissue damage and/or bronchospasm associated with chronic bronchitis can sometimes be due to an immunologic mechanism; 2) if an immunologic mechanism is involved in some cases, to learn which of several mechanisms is operative; 3) if a specific organism or strain of organism, even organisms currently classified as non-pathogenic, will elicit allergic reactions in certain patients with chronic bronchitis which are not observed when the same organism is tested on other subjects with chronic bronchitis; and 4) the possible role of an isolated lack of an immune mechanisms against usually non-pathogenic organisms is perpetrating chronic sino-tracheal bronchitis in some patients with or without hyperreactive airways.